1. Field of the Invention
The present invention relates to an actuator locking mechanism for an information storage device, and more particularly to a locking mechanism and a locking method which make use of a magnet and enhance a locking force with respect to impact force.
2. Description of the Related Art
In information storage devices that are represented by a magnetic storage device, a transducer for reading and/or writing data is attached to an actuator, and the actuator is driven so that the transducer scans a storage medium. When recording or writing is not performed, the transducer is retracted to the actuator's stop position away from the recording region of the storage medium. In order for the transducer not to be moved to the recording region, even if an external impact force is applied to a magnetic storage device when the actuator is in the stopped position, there is an actuator locking mechanism which locks the actuator to a base.
One example of an actuator locking mechanism is a fixed magnet type locking mechanism, such as that described in Published Unexamined Patent Application No. 5-151737. The fixed magnet type locking mechanism attracts a portion of the actuator in its stopped position with a permanent magnet fixed to the base of the magnetic storage device to lock the actuator, and has the feature that it is simple in structure and easy to miniaturize. However, when impact force sufficient to move an actuator is applied to the magnetic storage device, an actuator being locked to the base by magnetic attraction is not allowed to move in the attracted state at all and therefore the impact force to the actuator is applied directly and entirely to the attracting surfaces. Since there is a limitation on an enhancement in the magnetic attraction, the attracting surfaces of the permanent magnet and the actuator cannot be attracted enough to lock the actuator to the base with respect to a large impact force applied to the actuator. Moreover, the recent miniaturization and portability demand for a computer having a magnetic storage device mounted therein requires a further miniaturization in the magnetic storage, which also sets limits on the size of the magnet being increased in order to enhance the locking force of the locking mechanism, further increases the magnitude of impact force that is applied to the magnetic storage device, and gives further impetus to the problem that the actuator cannot be locked sufficiently in the stop position.
Another locking mechanism disclosed in Published Unexamined Patent Application No. 5-151737, is a solenoid type locking mechanism provided with a solenoid and a mechanical latching mechanism. Although the solenoid type can sufficiently obtain a force for locking an actuator, the solenoid type locking mechanism becomes complicated in structure and is increased in size, as compared with the magnet type locking mechanism. Consequently, the solenoid type is not sufficiently satisfactory as an actuator locking mechanism for a magnetic storage device demanding miniaturization and portability.
As previously described, the conventional actuator locking mechanism has the disadvantage that it cannot exhibit a strong locking force with a small size, while the solenoid locking mechanism is complicated in structure. Accordingly, it can be seen from the problems described in the prior art that there is a need to provide a magnetic actuator locking mechanism equipped with an even stronger locking force, while allowing the device size to be reduced and maintaining a simple structure.